Curious Behavior Found in Spin Ice Thin Films

According to the Third Law of Thermodynamics, as an object approaches absolute zero, its entropy will also approach zero. For just about every material this is true, but spin ice has been a curious exception. Now researchers at University College London have discovered a means to restore the Third Law in spin ice thin films, which could lead to some very interesting applications.

For conventional materials, the randomness of their atoms, or entropy, will reduce as they cool, because they will tend towards a specific low energy state. Spin ice however does not have a single low energy state for the spins of the atoms within it. This leads to some interesting properties, including the violation of the Third Law and the ability to create magnetic monopoles. The UCL researchers however have found that a thin film, just nanometers thick, can be made to obey the Third Law. This is because of the strain the material is subjected to by its substrate.

This ability to effectively toggle the Third Law of Thermodynamics on and off could enable some interesting manipulations of magnetic monopoles and potentially magnetricity, the magnetic equivalent of electricity. This could also have an impact on data storage as HDDs rely on thin magnetic films to store information.